chris@mimsy.umd.edu (Chris Torek) (12/07/90)
>kls30@duts.ccc.amdahl.com (Kent L Shephard) writes: >>... you have to get a PMMU on a 68020 which adds wait >>states to memory. Many Sun machines use a private MMU which does not (depending on machine) add wait states, and of course the '020 has a 256-byte I-cache that the 386sx lacks. Virtual caches can also help eliminate the MMU delays. The lack of 32-bit bus access in 386 mode is a serious speed impediment (of course one can always use a *real* 80386, rather than the crippled version). [End of Sun & architecture stuff.] >>... resolution is the number of pixels, dot pitch determines >>dpi. Look at any number of publications and manufacturer's literature >>and resolution is listed as 800x600, 1024x768, etc. In article <1990Dec7.030303.20157@julius.cs.uiuc.edu> coolidge@cs.uiuc.edu (John Coolidge) writes: >Manufacturers who don't understand English, either conversational >or technical. Resolution has a very clear and precise meaning, and >it isn't the number of dots on your (arbitrarily big) monitor. >[resolution is a measure of grain per unit area, e.g., dpi] John is right, Kent is misled; these manufacturers are either stupid, lazy, or conniving (or some combination thereof). 1024 pixels across is very high resolution if the pixels are spaced uniformly over a line one micrometer long, and very low resolution if the pixels are spaced uniformly over a line one megaparsec long. (The dots on the latter are approximately 1E21 inches apart. [Yes, I am one of those people who runs `units' to compute furlongs per fortnight.... 55 mph is about 10500 furlongs per day.]) >>If I'm not mistaken the 68k is circa 8086. (I have no idea what this sentence is supposed to mean.) >[The 80x86 series is compatible with a 1980-or-earlier design, the 680x0 > series with a 1982-3 design; the former has a stronger negative effect > on the designer's abilities to make chips that run fast.] (I hope this paraphrase of John's wording is close enough) I am not sure of the relative timings of 8085, 8086, and 8088, but as a high school student I worked for a company that was using the 8085 in their microwave measurement instrument (the VM-4, for anyone who has heard of Weinschel); this was designed before 1979, so the 8085 had to be available by 1978 at the latest. -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@cs.umd.edu Path: uunet!mimsy!chris